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hrtimer: Fix hrtimer_is_queued() hole

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A queued hrtimer that gets restarted (hrtimer_start*() while
hrtimer_is_queued()) will briefly appear as unqueued/inactive, even
though the timer has always been active, we just moved it.

Close this hole by preserving timer->state in
hrtimer_start_range_ns()'s remove_hrtimer() call.

Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: ktkhai@parallels.com
Cc: rostedt@goodmis.org
Cc: juri.lelli@gmail.com
Cc: pang.xunlei@linaro.org
Cc: wanpeng.li@linux.intel.com
Cc: umgwanakikbuti@gmail.com
Link: http://lkml.kernel.org/r/20150611124743.175989138@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Peter Zijlstra 2015-06-11 14:46:45 +02:00 committed by Thomas Gleixner
parent c04dca02bc
commit 8edfb0362e
1 changed files with 13 additions and 10 deletions
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23
kernel/time/hrtimer.c
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@ -889,10 +889,10 @@ static void __remove_hrtimer(struct hrtimer *timer,
* remove hrtimer, called with base lock held
*/
static inline int
remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base)
remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base, bool restart)
{
if (hrtimer_is_queued(timer)) {
unsigned long state;
unsigned long state = timer->state;
int reprogram;
/*
@ -906,12 +906,15 @@ remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base)
debug_deactivate(timer);
timer_stats_hrtimer_clear_start_info(timer);
reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
/*
* We must preserve the CALLBACK state flag here,
* otherwise we could move the timer base in
* switch_hrtimer_base.
*/
state = timer->state & HRTIMER_STATE_CALLBACK;
if (!restart) {
/*
* We must preserve the CALLBACK state flag here,
* otherwise we could move the timer base in
* switch_hrtimer_base.
*/
state &= HRTIMER_STATE_CALLBACK;
}
__remove_hrtimer(timer, base, state, reprogram);
return 1;
}
@ -936,7 +939,7 @@ void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
base = lock_hrtimer_base(timer, &flags);
/* Remove an active timer from the queue: */
remove_hrtimer(timer, base);
remove_hrtimer(timer, base, true);
if (mode & HRTIMER_MODE_REL) {
tim = ktime_add_safe(tim, base->get_time());
@ -1005,7 +1008,7 @@ int hrtimer_try_to_cancel(struct hrtimer *timer)
base = lock_hrtimer_base(timer, &flags);
if (!hrtimer_callback_running(timer))
ret = remove_hrtimer(timer, base);
ret = remove_hrtimer(timer, base, false);
unlock_hrtimer_base(timer, &flags);